The liquid residue, as well as the combustion gases are highly corrosive and dangerous to the walls of the furnace. The tendency is towards higher steam pressure and higher temperature, whereby the risk for corrosion attacks will increase. The primary combustion occurs under reducing conditions, which imparts certain requirements upon the shape of the combustion chamber, and upon the arrangements for the supply of combustion air.
There will always be a certain amount of said particles in the arising combustion gases, and these particles will adhere to the heat exchange surfaces of the convection part of the boiler, clogging these surfaces. When the plant is shut down for surveying the furnace dropping lumps of such particles is an obvious danger.
The aim of the present invention is to provide a plant, suited to burn waste liquor and similar fuels producing a liquid combustion residue, which is advantageous with respect to manufacture and safe with respect to corrosion, and combines high combustion capacity with favourable combustion properties, and which further permits repair and upkeep to be performed under safe conditions.